1. Field of the Invention
The present invention relates to an information card, which is typically, but not exclusively, a PC card, and to a card shaped casing for such an information card.
2. Description of the Related Art
Conventionally, information cards are commonly used for adding new functions or increasing functionality of information processing devices such as personal computers (PC), personal digital assistants (PDAs) and other communication devices. The information cards are constructed by installing various electronic components and electronic circuits in a card shaped casing. With regard to the information cards for PCs, PC cards that adhere to standards according to the Personal Computer Memory Card International Association (PCMCIA) or the Japan Electronic Industry Development Association (JEIDA) are generally used. There are two types of PC cards including a first type for 16 bit bus width, and a second type which follows the CardBus standards, is for 32 bit bus width. Although the two types of PC cards differ from each other with respect to, for example, whether or not they require ground plates, or other features, the constructions thereof are basically the same. The basic construction of a conventional PC card is shown in FIGS. 5 and 6.
With reference to FIG. 5, a PC card includes a rectangular and flat frame 10, a front panel 12, and a back panel 14. The frame 10 is generally constructed of a resin, and the front panel 12 and the back panel 14 are generally constructed of metal plates. Various electronic components and electronic circuits (printed patterns) are mounted or formed on a printed board 16, which is disposed in a space surrounded by the frame 10, the front panel 12, and back panel 14. The frame 10 defines the side surfaces of this space, and the front panel 12 and the back panel 14 defines the front and the back surfaces of this space. The electronic components and the electronic circuits on the printed board 16 are connected to an external device via a front connector 18 or via a back connector 20 provided in the frame 10. The front connector 18 is disposed at one end of the PC card that is first inserted into a card-receiving slot, and the back connector 20 is disposed at the other end of the PC card. For example, with respect to memory cards, memory cells and memory circuits provided on the printed board 16 are connected to devices inside personal computers via the front connector 18. In this case, the back connector 20 may be omitted. With respect to modem cards, LAN cards, and other types of cards, the front connector 18 is required for connecting the card to the devices inside personal computers, and the back connector 20 is also required for connecting the card to external wirings.
The front panel 12 and the back panel 14 are fixed to the frame 10 by, for example, thermocompression bonding. With reference to FIG. 6, the front panel 12 is constructed by forming an insulating layer 24 on an inwardly facing surface of a stainless steel plate 22 that is arranged to oppose the printed board 16, and by forming an adhesive layer 26 on the insulating layer 24. The back panel 14 is constructed in a similar manner. The front panel 12 and the back panel 14 are first aligned against the frame 10 in which the printed board 16 is disposed, and then the process of thermocompression bonding is performed. Accordingly, the front panel 12 and the back panel 14 are fixed to the frame 10. The insulating layer 24 insulates the electronic components and the electronic circuits on the printed board 16 from the front panel 12 and the back panel 14. In addition, the stainless steel plates are included in the front panel 12 and the back panel 14, and the grounded lines included in the printed board 16 are connected thereto. Accordingly, the mechanical strength of the PC card is ensured, and the electronic components and the electronic circuits are electromagneticaly shielded from the exterior of the PC card.
As described above, two panels (the front panel and the back panel) are used in the conventional PC card, and each panel includes a plate constructed of stainless steel or other metal having conductivity and rigidity, an insulating layer, and an adhesive layer. Thus, the construction is complex and the manufacturing cost is high. Accordingly, there are limits to reducing the number of components required for manufacturing the PC card, and to reducing the manufacturing cost.
To solve such problems, a method disclosed in Japanese Unexamined Patent Application Publication No. 6-320892 is useful, which will be referred to as a xe2x80x9cpublished techniquexe2x80x9d in the following descriptions. In this published technique, a half of the frame that is located near the front panel is unitarily formed with the front panel, and the remaining half of the frame which is near the back panel is unitarily formed with the back panel. In addition, the front panel which is unitarily formed with the front half of the frame and the back panel which is unitarily formed with the back half of the frame are constructed of a resin. Accordingly, panels constructed of metal are not used. When this technique is applied to PC cards, the number of components and the manufacturing costs are reduced compared to the conventional technique described with reference to FIGS. 5 and 6.
In the above-described published technique, however, the shapes and the constructions of the front panel and the back panel are complex compared to the conventional technique, since each panel is unitarily formed to define a half of the frame. According to the published technique, two members (the front panel which is unitarily formed with the front half of the frame and the back panel which is unitarily formed with the back half of the frame) must be prepared, each of which has a complex shape and construction. Thus, in the case in which the published technique is applied to a PC card, there is another limit to reducing the cost and difficulty of manufacturing the case.
In addition, since the front panel and the back panel are constructed of a resin, the structural strength is reduced and the electromagnetic shielding ability is degraded compared to the conventional technique, in which the front and the back panels are constructed of a metal. To increase the structural strength, the front and the back panels of the published technique are provided with plate-shaped projections on the surfaces that are arranged opposite to the printed board, so as to provide reinforcing members. However, such reinforcing members increase the complexity of the shapes and the manufacturing steps of the front and the back panels, and the reduction of the manufacturing cost is further impeded.
In addition, in the conventional technique shown in FIGS. 5 and 6, the front and the back panels constructed of a metal are adhered on the frame constructed of a resin. Thus, a material which is capable of fixing the metal and the resin is used for forming the adhesive layer 26. In contrast, in the published technique, the front and the back panels are both constructed of a resin, and a double-sided adhesive tape is applied for fixing the front and the back panels to each other. Accordingly, when a manufacturer introduces the published technique in place of the conventional technique shown in FIGS. 5 and 6, the adhering method and the adhesive must also be changed. Thus, additional expenses for technological development and for obtaining manufacturing know-how is required.
In order to overcome the problems described above, preferred embodiments of the present invention provide an information card and a card shaped casing therefor which require few components, which are developed and manufactured at low cost, and in which the structural strength is sufficient and electromagnetic shielding is ensured.
To this end, a card shaped casing of a preferred embodiment of the present invention preferably includes a panel-combined frame having a frame portion and a panel portion, the frame portion defining side surfaces of an information card, the panel portion defining the front surface or the back surface of the information card, and a separate panel which is arranged to oppose the panel portion of the panel-combined frame across the frame portion of the panel-combined frame, and which defines the back surface or the front surface of the information card, and electronic components or electronic circuits are disposed in a space surrounded by the panel-combined frame and the separate panel.
An information card according to another preferred embodiment of the present invention preferably includes the above-described card shaped casing and a board on which the above-described electronic components and the electronic circuits are mounted.
Since the panel-combined frame is used, in which a frame and one of front and back panels define a unitary, integral member, the number of panels is reduced compared to the conventional technique shown in FIGS. 5 and 6, so that the cost is reduced. The construction of the panel-combined frame is more involved compared to the panels used in. the conventional technique shown in FIGS. 5 and 6. However, only one panel-combined frame is necessary, so that the card shaped casing of preferred embodiments of the present invention is manufactured at a lower cost compared to the published technique, in which two panels having complex shapes and constructions are used.
The panel-combined frame and the separate panel may both be constructed of a metal. In such a case, the structural strength is increased and the electromagnetic shielding ability is greatly improved compared to the published technique.
The construction of the card shaped casing may be such that one of the panel-combined frame and the separate panel is constructed of a resin, and the other one of the panel-combined frame and the separate panel is constructed of metal. Also in this case, the structural strength is increased and the electromagnetic shielding ability is improved compared to the published technique. In addition, the panel-combined frame and the separate panel can be adhered to each other by the same method as that used in the conventional technique shown in FIGS. 5 and 6 for adhering the frame and the panels to each other. Accordingly, development cost is also reduced. The number of places to be adhered is reduced, so that mechanical strength is stabilized, and cost is further reduced. One of the panel-combined frame and the separate panel which is constructed of a resin may be covered with a layer which functions as an electromagnetic shield. In such a case, the ability to electromagnetically shield the electronic components and the electronic circuits disposed in the card shaped casing from the exterior of the card shaped casing is greatly improved. The layer which functions as an electromagnetic shield may also be provided on a board disposed in the card shaped casing on a surface which is opposite to the panel-combined frame and the separate panel which is constructed of a resin. Also in this case, the ability to electromagnetically shield the electronic components and the electronic circuits disposed in the card shaped casing from the exterior of the card shaped casing is greatly improved. In addition, when one of the panel-combined frame and the separate panel is constructed of a resin, it is possible to manufacture colored or colorless, transparent or translucent, panel-combined frames and separately formed panels, in accordance with a material of resin or a manufacturing condition. In addition, one of the panel-combined frame and the separate panel which is constructed of a metal may be used as a conductor for achieving the ground connection between the electronic components and the electronic circuits disposed inside the card shaped casing and the exterior of the card shaped casing. In such a case, the number of components is further reduced.
According to another preferred embodiment of the present invention, a card shaped casing preferably includes a frame having a flat shape which defines side surfaces of an information card, and a front panel and a back panel which respectively define the front surface and the back surface of the information card, and which oppose each other across the frame, and one of the front panel and the back panel is constructed of a resin and the other one of the front panel and the back panel is constructed of a metal, and electronic components and electronic circuits are disposed in a space surrounded by the frame, the front panel, and the back panel. When one of the front panel and the back panel is constructed of a resin as described above, the card shaped casing having an excellent structural strength compared to the published technique is achieved.
Other features, elements, arrangements, characteristics and advantages of the present invention will become more apparent from the detailed description of preferred embodiments of the present invention with reference to the attached drawings.